This invention relates to immunological protection against Vibrio cholerae.
V. cholerae is a bacterial species that can cause a diarrheal disease in humans by colonizing in the small intestine and secreting a protein toxin. The action of the cholera toxin has been well characterized. The toxin includes two subunits, the A and B subunits; the B subunit has no known toxic activity but provides a degree of immunological protection when used as a component of a vaccine. Black et al. 1986 In Advances in Research on Cholera and Related Diarrheas 3:271. eds. Kuwahara et al.
In addition to B sub-unit vaccines, vaccines for cholera also include denatured whole cholera toxin, killed whole cells of V. cholerae grown usually on a solid medium at pH 7.5-8.0, and mixtures of killed cells and inactivated toxin molecules. Other vaccines include live attenuated V. cholerae strains which do not produce the A subunit of cholera toxin, and attenuated strains of heterologous non-Vibrio cholerae carriers, that is, non-V. cholerae strains, e.g., Salmonella typhi Ty21A having cloned genes encoding the cholera protective 01 antigen (J. Infectious Desease 131:553-558, 1975).
Ehara et al. (Trop. Med. 28:21, 1986; and Vaccine, 1988) describe purification of fimbriae of V. cholerae having a structural subunit protein of about 16 kD. This protein is not stained by Coomassie blue and its haemagglutination (HA) titre is mannose sensitive. AL-Kaissi et al. (J. App. Bact. 58:221, 1985) also describe fimbriae which have a mannose sensitive HA titre.
Kanoh (Nippon Saikingaku Zasshi, 36:465, 1981), Melnikova et al. (Mol. Biol. Genet. Russian 2:18, 1982), and Kanoh (Jpn. J Bacteriol. 36:465, 1981) describe sex pili of V. cholerae, encoded by plasmid genes. Holmgren et al (Infect. Immun. 33:136, 1981) describe various E. coli fimbriae.